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Serum Creatinine (with optional 24-hour urine collection for creatinine clearance calculation)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of creatinine, a waste product from muscle metabolism, in your blood or urine. It helps assess kidney function.

Quick summary

["Kidney function and filtration efficiency are evaluated with creatinine levels."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
60641-8
Short code
Sti-Me' Skull XR
Synonyms
Sti-Me' Skull XR
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
xr-measured
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order a creatinine test to check how well your kidneys are working. High levels can indicate kidney disease or damage, while low levels might suggest dehydration or muscle loss. It’s often used alongside other tests to monitor chronic conditions like diabetes or heart disease.

What to Expect Before the Test

For a blood test, you’ll typically have a small needle inserted into your arm. No special preparation is needed unless your doctor specifies otherwise. If a 24-hour urine sample is required, you’ll collect all urine over 24 hours in a container provided by your lab.

What the Results Mean

Creatinine levels alone don’t diagnose kidney disease, but they help assess kidney function relative to your body size. Your doctor will compare your results with your baseline and other health factors, such as blood pressure or diabetes status.

Common Conditions Monitored

This test is used to monitor kidney function in conditions like chronic kidney disease, diabetes, or heart failure. It can also help detect early signs of kidney problems before symptoms appear.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High creatinine levels may signal reduced kidney function, which can increase risks for heart disease, blood pressure issues, or other complications. Low levels might indicate fluid overload or muscle wasting. Regular monitoring helps manage these risks and adjust treatments as needed.

Short name

Creatinine

Frequently asked questions

What causes creatinine levels to change?
Several factors can affect creatinine levels, including muscle mass (higher muscle mass can raise levels), dehydration, or certain medications. Kidney disease, heart problems, or severe infections can also alter results. If you’ve had recent surgery, trauma, or changes in diet (e.g., high-protein foods), let your doctor know.
Your doctor will determine how often you need this test based on your health condition. For example, people with diabetes or kidney disease may need it more frequently than others. Follow-up tests are often scheduled every few months or years, depending on your situation.
Yes, diet and exercise can influence creatinine levels. Eating a high-protein diet temporarily increases muscle breakdown, which may raise creatinine levels. Staying hydrated helps maintain normal kidney function. Exercise generally supports kidney health, but intense workouts or dehydration can temporarily affect results.
What should I do if my creatinine level is unusually high?
If your creatinine level is elevated, your doctor may recommend further testing or adjustments to your treatment plan. They could also check for underlying causes like kidney disease, dehydration, or other health issues. Never delay seeking medical advice if you notice changes in your test results.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy